In the water hydrant industry it is desirable to build outdoor hydrants that are easy to install, freeze proof and that can prevent undesirable flows such as backflow where contaminated water from outside a hydrant might flow back into the hydrant and the hydrant water supply.
U.S. Pat. No. 3,952,770 to Botnick shows one prior art approach to an outdoor hydrant. The hydrant of Botnick is typical in terms of its difficulty to install. The hydrant has a face 60 designed to mount against the surface of a building but the cross section shape behind the face is very complex making the hydrant difficult to mount. In a new installation typically a large hole is left until the hydrant is installed and then the wall is filled in around the hydrant. To retrofit the hydrant in an existing wall a worker will drill a hole large enough for the pipe (A) and possibly several smaller holes and then has to carve out around the hole using a chisel or whatever tool he might have to hand carve the opening to match the cross sectional shape of the hydrant. The sealing stopper of Botnick rotates and moves longitudinally as it seals leading to excessive wear on the seals.
U.S. Pat. No. 5,158,105 to Conway discloses an anti-freeze hydrant 1 having a pipe section 22 that connects the operator near cap 50 to the valve 65. Conway uses a rotating shaft 33 to connect to the valve 65 which can close sequentially. In the valve closed position water can drain from the hydrant. One undesirable effect of Conway is that the operator end of the shaft 33 moves longitudinally in and out of the cap 50. Another is that the seals 35, 65 can experience increased wear due to the combination of rotational and longitudinal movement.
As can be seen there is a need for a hydrant that is easy to install and maintain. There is also a need for a hydrant that has a dual back flow preventer in a compact design. There is further a need for a hydrant that prevents freezing and undesirable backflow.